JP-A-2006-140311 discloses a technique of forming a polyvinyl alcohol (PVA) film on the surface of a semiconductor substrate before the semiconductor substrate is diced by a laser beam. The polyvinyl alcohol film serves as a protection film for preventing foreign materials which occur in the dicing process from adhering to the semiconductor substrate. Accordingly, the polyvinyl alcohol film as well as the foreign materials adhering to the semiconductor substrate are removed by water washing.